1. Field of the Invention
The present invention relates to a dual clutch transmission comprising a first clutch to be engaged for setting any one of a plurality of forward-traveling odd-numbered speeds and a second clutch to be engaged for setting any one of a plurality of forward-traveling even-numbered speeds, wherein a desired forward-traveling speed is caused by alternately engaging/disengaging the first and second clutches, and wherein a backward-traveling drive train is adapted to be activated by engaging one of the first and second clutches.
2. Related Art
As disclosed in JP 2003-269592, there is a well-known dual clutch transmission which receives power from a prime mover and is automatically gearshifted to change the speed of the output rotary power transmitted to an axle. The dual clutch transmission comprises a group of odd-numbered speed gear trains, a group of even-numbered speed gear trains, a first clutch, and a second clutch. When one of the odd-numbered speed gear trains is selected to be activated, the selected odd-numbered speed gear train is activated by engaging the first clutch, i.e., receives power from the prime mover through the engaged first clutch. When one of the even-numbered speed gear trains is selected to be activated, the selected even-numbered speed gear train is activated by engaging the second clutch, i.e., receives power from the prime mover through the engaged second clutch.
During the gearshift of the dual transmission between neighboring odd and even numbered speeds, the next speed gear train is selected while the current speed gear train still remains engaged, i.e., the current speed gear train and the next speed gear train are simultaneously selected to be driven, and then one of the first and second clutches having been engaged for activating the current speed gear train is disengaged while the other of the first and second clutches is engaged so as to activate the next speed gear train, i.e., the engagement and disengagement of the first and second clutches overlap, thereby ensuring gearshift without intermittence of power transmission.
However, when a working vehicle equipped with the dual clutch transmission is a utility vehicle equipped with a loader, and the vehicle frequently reverses its forward/backward traveling direction for removing snow by use of the loader, for example, the gearshift of the conventional dual clutch transmission for reversing the traveling direction is gradually performed by shifting down the forward traveling speed step by step to the neutral state before setting the backward traveling speed. This gearshift takes a long time which spoils the workability and requires this vehicle to travel a long distance.